1. Technical Field
The present invention relates to a projector system having an information processing apparatus supplying image data on which an image process is performed to a projector and the projector projecting an image based on the image data supplied from the information processing apparatus, a projector used for a projector system, and an information processing apparatus used for a projector system.
2. Related Art
In a projector system having an information processing apparatus (personal computer or the like) supplying image data on which an image process is performed to a projector and the projector projecting an image based on the image data supplied from the information processing apparatus, the image data to be displayed by the projector is generally transmitted as an analog signal from the information processing apparatus.
Accordingly, image data which is kept as digital data by the information processing apparatus is converted into an analog signal in advance by the information processing apparatus and then sent to the projector. In the projector, the analog signal transmitted from the information processing apparatus is converted into a digital signal, and image processes including a correction process are performed on the digital signal.
Recently, owing to the improvement of the performance of a CPU or a GPU for an information processing apparatus, a projector system in which image processes including a correction process (for example, form conversion, color correction) are performed in the information processing apparatus side, and image data (digital data) to be displayed by the projector is sent to the projector through a USB cable or the like has been proposed.
In this type of projector systems, since image data (digital data) on which the image process including a correction process is performed is sent to the projector, the image process including the correction process not required in the projector side. These types of projector systems are called host-based projectors. The host-based projectors can be configured to have minimal components required for projection, and accordingly, the host-based projectors can be manufactured small and inexpensive.
However, in a projector system using the host based projector, software for performing an image process (including a correction process) which is installed in the information processing apparatus along with the projector itself has a high value.
Accordingly, it is possible to produce and sell a projector so-called a pirated edition by a malignant user's combining the software and a projector (referred to as a non-formal projector) other than a formal one which forms a set with the software.
A technology to cope with this problem, for example, is disclosed in JP-A-2003-69923. In the technology, a password generated by the projector side is acquired by the information processing apparatus side, and the information processing apparatus side performs encryption, for example, using a WEP (Wired Equivalent Privacy) method, on image data to be sent to the projector using the acquired password each time the image data is sent, the encrypted image data is sent to the projector, and the projector side decrypts the encrypted image data sent from the information processing apparatus each time the encrypted image data is received and performs displaying.
As described above, in the technology disclosed in JP-A-2003-69923, the security of the software is acquired by encrypting image data and the like using a password for each new image and sending the encrypted image data and the like to the projector.
The technology disclosed in JP-A-2003-69923 is useful for acquiring the security of software.
However, in the technology, it is required that the information processing apparatus side encrypts the whole image data to be sent to the projector whenever the image is sent, the encrypted image data is sent to the projector, and the projector decrypts the encrypted image data whenever the encrypted image data is received. Moreover, since decrypting the encrypted image data at any time when the encrypted image data is received requires corresponding preparation of hardware and software in the projector side, the configuration and process of the projector becomes complex.
The main purpose of the projector system using a host-based projector is to simplify the configuration, and process of the projector by having the information processing apparatus side perform more processes, thereby lowering the development costs to lower the price of the product. Accordingly, the technology of decrypting encrypted image data each time when the encrypted image data is received, as the above-described technology which is disclosed in JP-A-2003-69923, is preferable in terms of acquiring the security of the projector, but there is a problem in that the advantage of a host-based projector cannot be taken fully.